To produce effective caudal anesthesia, anesthesiologists should be selective about the patients in whom it is attempted. It makes no sense to use the technique in a patient whose anatomy is unfavorable. Because of the anatomic variations in the area around the sacral hiatus, this block seems to require more operator experience and a longer time to attain proficiency than many other regional blocks. As a result, anesthesiologists should develop their technique in patients whose anatomy is favorable.

One helpful hint that can confirm needle location when carrying out caudal anesthesia is illustrated in
Figure 50-8
. Once the needle has entered what is thought to be the caudal canal, the anesthesiologist should place a palpating hand across the sacral region dorsally. Then 5 mL of saline solution should be rapidly injected through the caudal needle. By placing the hand as shown, the anesthesiologist should be immediately aware of the subcutaneous needle position overlying the sacrum. If the needle is mispositioned subcutaneously, a “bulge” during injection develops in the midline. If the needle is correctly positioned in the caudal canal, no midline bulge should be palpable. It is emphasized that in thin individuals accurate needle placement in the caudal canal and rapid injection of solution may allow the anesthesiologist to feel small pressure waves more laterally, overlying the sacral foramina. These pressure waves should not be confused with those associated with a misplaced subcutaneous needle.